Manufacture of trimethylene diamine and n-propylamine



- x 3 rss 5% MANUFACTURE on iuuiymTr-IYLENE nrAMmE AND N-PRUPYLAMINE Arthur F. Miiler, Cleveland, and Wilfred ll. Howsmon, Jr., Marietta, Chin, assignors to The Standard- Oil Company, Cleveland, (ihio, a corporation of Ghio No Drawing. Filed May 3, 1962, Ser. No. 192,044 Claims. (Cl. 260 583) The present invention relates to a process for the simultaneous manufacture of trimethylene diamine and n-propylamine. According to the process of this invention a mixture comprising acrylonitrile, hydrogen and aqueous ammonia is reacted under relatively mild conditions in the presence of a hydrogenation catalyst to yield the desired products.

It has been suggested in the prior art that tnmethylene diamine may be prepared from acrylonitrile by reacting acrylonitrile with an excess of anhydrous ammonia and subsequently hydrogenating the resulting reaction product in thepresence of a-hydrogenation catalyst. According to this suggestion the catalyst is conventiona1 and it may be selected from the metalsof Groups V to VIII of the Periodic System or their compounds, for example the oxides of sulphides of these metals and their, alloys may be employed in carrying out this process. Preferred catalysts are cobalt and/ or nickel or their compounds especially the oxides of these metals. The suggested reaction conditions are temperatures in the range of 20 to 200 C. and pressures on the order of to 500 atmospheres. According to this teaching the best results are obtained when a fairly substantial excess of ammonia is present in the reaction mixture; I

Experiments conducted following this suggestion of the prior art have shown that the activity of the catalyst diminishes rapidly upon use and in order to obtain the optimum results it is necessary as a practical matter to prepare each batch of trimethylene diamine with a catalyst whichis fresh or one that is nearly so. Accordingly, a method of producing trimethylene diamine from acrylonitrile which is not attended by a loss of activity of the catalyst would obviously be economically advantageous and it is the principal object of this invention to provide such a process. process: for the "simultaneous production of trimethylene diamine and n-propylamine. T' i In brief, the process of' this invention is carried out by reacting a mixture comprising acrylonitrile, aqueous ammonia and hydrogen in the presence of a hydrogenation catalyst under relatively mild reaction conditions which will'be described more fully hereinafter.

' It was quite surprising and unexpected to find that the addition of even a minor amount of water to the reaction mixture was successful in preventing any substantial loss of activity of the hydrogenation catalyst. The manner in which the water behaves in the system is not fully understood but it has been hypothesized that the water serves as a catalyst in the cyanoethylation of ammonia since it has been observed that the ammonia and acrylonitrile react much more rapidly in the presence of water. The theory which'explains thefunction of the Water is unimportant to an understanding of this invention, since Another object of this invention is-to provide a Patented Jan. 19, 1965 aluminum alloy and cobalt-copper powder. The methods by which thesecatalysts areprepared' are not critical and any of the well-known methods of preparing such catalysts may be employed. If desired the catalyst may be used in conjunction with a support material which is inert under the process conditions. r v

The nature of the catalyst employed in the process appears to have a pronounced influence on the kind and the amount of amine which will be produced. If a substantial amount of n-propylamine as well as trimethylene diamine is desired, a catalyst based on nickel should be employed. Gn the other hand, if it is desired to minimize the production of n-propylarnine, a catalyst based on cobalt should be employed in the process. It should be clearly understood, however, that the use of either'the nickel or cobalt catalysts will result in the production of both trimethylene diamine and n-propylarnine and that the choice of the catalyst will affect only the relative amounts of each compound which will be produced.

One variable in the process isthe Weight ratio of the catalyst to acrylonitrile. In general higher ratios of'catathe observed phenomena clearly show the advantageous results which are derived by the addition of water to the reaction mixture. n

The hydrogenation catalyst which'is employed in-the process of this invention may be selected from the metals lyst to acrylonitrile result in an increase in the amount of n-propylamine produced with an attendant decrease in the amount of trimethylene diamine produced. It appears that the optimum results from the standpoint of the production of a maximum amount of trimethylene diamine are obtained when the weight ratio of catalyst to acryllonitrile is about 0.2.

The process may be carried out at reactor temperatures in the range of to 350 C., and preferably between to C. The pressure within the reactor should be in the range of 15 to 200 atmospheres and preferably in the range of 25 to 50 atmospheres. In order to insure that the reaction will go to completion, reaction times on the order of about 1 to 5 hours should be employed.

One of the more important variables in the process is the ratio of ammonia to acrylonitrile. In general, the molar ratio of ammonia to acrylonitrile should be in the range of 5:1 to about 40:1, and a preferred ratio for the production of trimethylene diamine appears to be about 20:1. Ratios near the upper end of the stated range favor the production of trimethylene diamine at Y the expense of n-propylamine.

The'anwunt of water which is to be added to the reactionmixture must be carefully controlled. The lower 7 limit on the amount of water is not critical and even very small amounts will serve to prolong catalyst life.

However, there is a critical upper limit on the amount 1 For convenience, it may be desirabletoemployj a com- V merical aqueous ammonia (28% by weight'"NI-I as a raw material in the process and this will give a ratio '0 2.31 moles of water per mole of ammonia.

general, the process is conducted in a-batch reaction vessel, with relatively pure hydrogen being used both to pressurize the system and'to provide the-hydrogen necessary to the formation of thedesired endproducts.

The product mixture obtained in theprocess may be worked up by conventional separation techniquessuch as fractional distillation in order to recover and separate v. trimethylene diamine and n-propylamine. 1 Unreacted annnionia, acrylonitrile and h'ydrogenmay be recovered from the product mix and recycled in the process.

In order to: illustrate the effect of the presence of. water o n the. activity of the catalyst, a series of batch aisas as I reactions were conducted employing a conventional Raney nickel catalyst. In the first series which is illustrative of the prior art, liquid anhydrous ammonia was employed. The weight ratio of catalyst to acrylonitrile was 0.183 and the molar ratio of ammonia to acrylonitrile was 31. During these runs, the temperature of the reactor was maintained at 225 F. and it was pressured to 3000 p.s.i.g. with hydrogen. A uniform reaction time of two hours was allowed for each batch. The results, measured in terms of the percent of acrylonitrile converted to trimethylene diamine and n-propylarnine, are reported in the following table.

In a second series of runs which are illustrative of the present invention, an aqueous ammonia solution (28% by weight NH was substituted for the liquid anhydrous ammonia. The weight ratio of catalyst to acrylonitrile was 0.188 and the molar ratio of ammonia to acrylonitrile was 20.4. The temperature of the reactor was maintained at about 250 F. and the reactor was pressured to about 500 p.s.i.g. with hydrogen. A uniform reaction time of two hours was allowed for each batch. The results, reported on the same basis used in Table I, are set forth in the following table:

An examination of the data in Table I reveals that, when liquid anhydrous ammonia is employed, the activity of the catalyst falls 01f rapidly so that after only four batches the activity of the catalyst is almost nil. Y Onthe other hand, the data in Table II show that the catalyst does not undergo any appreciable decline in activity even after eleven batches have been run when water is added to the reaction mixture in accordance with the teachings of this invention. Moreover, the presence of water in the reaction mixture appears to afford a marked improvement in the amount of acrylonitrile which is converted to the desired end products, i.e. trimethylene diamine and npropylamine. i

As mentioned in the preceding paragraph, an additional advantage of the process of this invention is that the addition of even a small amount of water to the reaction mixture significantly improves the yield of .trimethylene diamine. In order to illustratethis point, two runs were conducted with a Raney nickel catalyst. Both of these 7 runs were conducted under the following conditions:

Reaction time2 hours Hydrogen pressure2850 p.s.i.g. Ammonia/acrylonitrile molar ratio'31 Catalyst/acrylonitrile wt. ratio0.188 Temperature-233 F.

However, in Batch A anhydrous ammonia was employed whereas in Batch B sutticient water was addedto the re.-

action mixture to provide a molar ratio of water to acrylonitrile of 0.1. The results are reported in the following table:

Hence, this data shows that the yield of trimcthylene diamine is improved more than three-told by the addition of a small amount of water to the reaction mixture.

Undoubtedly many modifications of the process described herein will occur to those skilled in the art, and this application for Letters Patent is intended to encompass all such modifications as would reasonably fall Within the scope of the appended claims.

We claim:

1. A process for the simultaneous production of trimethylene diamine and n-propylamine which comprises the step of reacting at a temperature in the range of 50 to 350 C. and a pressure of 15 to 200 atmospheres a mixture of acrylonitrile, ammonia, and hydrogen in the presence of a hydrogenation catalyst and water, said water being present in not more than about 10 moles per mole of ammonia.

2. A process for the simultaneous production of trimethylene diamine and n-propylamine which comprises the step of reacting at a temperature in the range of 50 to 350 C. and a pressure of from 15 to 200 atmospheres for from 1 to 5 hours a mixture of acrylonitrile, ammonia, and hydrogen in the presence of a Raney nickel hydrogenation catalyst and water, said water being present in not more than about moles per mole of ammonia.-

3. A process for the simultaneous production of trimethylene diamine and n-propylamine which comprises the step of reacting at a temperature in the range of 50 to 350 C. and a pressure of from to 200 atmospheres for from 1 to 5 hours a mixture of acrylonitrile, ammonia, and hydrogen in the presence of a Raney cobalt hydrogenation catalyst and water, said water being present in no more than about 10 moles per mole of ammonia.

4. A process for the production of trimethylene diamine which comprises the step of reacting at a temperature in the range of 50 to 350 C. and a pressure of from 15 to water to ammonia below about 10: 1.

8. A process for the simultaneous production of tll-' 200 atmospheres a mixture of acrylonitrile, ammonia, and hydrogen in the presence of a hydrogenation catalyst and water, said water being present-in not more than about 10 moles per mole of ammonia.

5. A process for the production of trimethylene diamine which comprises the step of contacting a mixture of acrylonitrile, ammonia, water and hydrogen said water being present in no more thanlO moles per mole of ammonia with a hydrogenation catalyst at a temperature in the range of 75 to 125 C. and at a pressure in the range of 15 to 200 atmospheres.

6. A process for the production of trimethylene diamine which comprises the step of contacting a mixture of acrylonitrile, ammonia, water and hydrogen with a hydrogenation catalyst at a temperature in the range of 75 to 125 C. and at a pressure in the range of 25 to atmospheres for from 1 to 5 hours, said mixture having a molar ratio of water to ammonia below about 10:1.

7. A process for the simultaneous production of tri- 'methylene diamine and n-propylarnine which comprises the step of contacting a mixture of acrylonitrile, ammonia, water and hydrogen with a Raney nickel hydrogenation catalyst at a temperature in the range of to C. and at a pressure in the range of 25 to 50 atmospheres for from 1 to 5 hours, said mixture having a molarratio of methylene diarniue and n-propylarnine which comprises the step of contacting a mixture of acrylonitrile, ammonia, Water and hydrogen with a Raney cobalt hydrogenation catalyst at a temperature in the range of 75 to 125 C. and at a pressure in the range of 25 to 50 atmospheres for from 1 to 5 hours, said mixture having a molar ratio of water to ammonia below about 1.

9. A process for the production of n-propylamine which comprises the step of reacting at a temperature of from 75 to 125 C. and at a pressure of from to atmospheres for a period of from 1 to 5 hours acrylonitrile and v 10. A process for the production of n-propylamine which comprises the step of reacting at a temperature of from to C. and at a pressure'ot from 25 to 50 atmospheres for a period of from 1 to 5 hours acrylonitrile and hydrogen in the presence of a Raney nickel hydrogenation catalyst and aqueous ammonia mixture, said mixture having a molar ratio of water to ammonia below about 10:l. 1

References (Iiteri in the file of this patent UNITED STATES PATENTS 2,287,219 Young et al. June 23, 1942 FOREIGN PATENTS Y 1 824,535 Great Britain Dec. 2, 19s 

1. A PROCESS FOR THE SIMULTANEOUS PRODUCTION OF TRIMETHYLENE DIAMINE AND N-PROPYLAMINE WHICH COMPRISES THE STEP OF REACTING AT A TEMPERATURE IN THE RANGE OF 50 TO 350*C. AND A PRESSURE OF 15 TO 200 ATMOSPHERES A MIXTURE OF ACRYLONITRILE, AMMONIA, AND HYDROGEN IN THE PRESENCE OF A HYDROGENATION CATALYST AND WATER, SAID WATER BEING PRESENT IN NOT MORE THAN ABOUT MOLES PER MOLE OF AMMONIA. 